The present invention relates generally to chair controls or chair irons for tilting chairs or tilting components of chairs. More particularly, the invention is directed to a chair control achieving utmost simplicity, neatness, compactness, reliability, and cost savings.
In a tilting chair the seat and back are firmly fastened together and the seat is mounted on a base providing pivotable movement. Tilting movement is supplied by a chair control disposed between the base and the chair seat. An energy package in the chair control resists backward tilting of the chair to effectively spring bias the chair in a generally upright position. Other types of chairs employing a chair control have stationary and tilting chair members. An example of such a chair is a secretarial chair having a chair back mounted for backward tilting movement relative to the seat. In this case the chair control spring biases the chair back into a generally upright position.
In general, these prior art chair controls suffer from a number of common disadvantages. In the prior art, the internal workings of the chair control are in the open and in many cases the stationary and pivoting frame members are relatively complex structures interconnected by a plurality of rivets and bolts. The extra work required when bolts and rivets are used for assembly of this type of structure slows the operation and materially adds to the cost of manufacture. Furthermore, the fact that the internal workings of the chair control, and in particular, the energy package are in the open present several problems. This type of open design presents a cluttered appearance, presents the possibility of pinching or catching material in the energy package and in general serve as a settling place for debris.
Attempts to at least partially enclose the internal workings of the chair control are found in the prior art. However, these prior art chair controls have always employed cast iron housings or folded enclosures. Cast iron enclosures are heavy, relatively expensive to manufacture and casting tolerances are not good. Folded enclosures generally enclose no more than three sides of the chair control, and are made of relatively thick metal in order to withstand the relatively high stresses imposed on the chair control. Use of relatively thick metal for the folded enclosure adds to the cost of manufacturing these types of chair controls. Such structures are difficult to fold and weld, and waste much of the sheet material from which they are formed. Also, the tolerances achieved with folded enclosures are still not high, and a relatively complex chair control is presented with many internal workings still exposed.
Another problem with prior art chair controls involves free-fall of the tilting chair member against its stops upon failure of the energy package or an associated component. Often this free-fall backward into the tilted position is violent enough to tip the chair backward and endanger the occupant.